Gas-fog alkylation with strong sulfuric acid and promoter

ABSTRACT

A PROCESS FOR ALKYLATION OF GASEOUS C2-C5 MONOOLEFIN WITH GASEOUS C4-C6 BRANCHED PARAFFIN COMPRISES CONTACTING THE MIXED GASES AT ALKYLATION CONDITIONS WITH A FOG OR MIST OF STRONG SULFURIC ACID AND A PROMOTOR. THE PROMOTER MAY BE RED OIL OR SPENT ACID FROM A CONVENTIONAL SULFURIC ACID ALKYLATION OR FROM A PREVIOUS RUN OF THE PRESENT PROCESS. PREFERABLY, THE CATALYST AND HYDROCARBON REACTANTS ARE MAINTAINED IN A CONCURRENT FLOW. FOR C3 OR C4 ACYCLIC MONOOLEFIN AND C4 OR C5 ISOPARAFFIN, THE PREFERRED ALKYLATION CONDITIONS INCLUDE A TEMPERATURE IN THE RANGE OF ABOUT 30-80*F. AND A PRESSURE ABOUT ATMOSPHERIC (E.G., 5-25 P.S.I.A., TYPICALLY 14-20 P.S.I.A.). THE FEED MOLE RATIO, PARAFFIN TO OLEFIN, CAN BE IN THE RANGE OF 1:1 TO 60:1, TYPICALLY 2:1 TO 30:1. LIQUID PARAFFIN (E.G., ISOBUTANE) CAN BE INJECTED INTO THE REACTOR IN ORDER TO CONTROL THE REACTION TEMPERATURE. PREFERABLY, THE LIQUID ACID DROPLETS HAVE A MEAN DIAMETER IN THE RANGE OF 5-50 MICRONS, TYPICALLY 10-25 MICRONS. AN ADVANTAGE OF THE PRESENT PROCESS IS A SUBSTANTIAL SAVINGS IN DISTILLATION COSTS REQUIRED TO SEPARATE ISOBUTANE FROM THE PRODUCT.

GAS-FOG ALKYLATION WITH STRONG SULFURIC ACID AND PROMOTER Filed May 5, 1972 4 Sheets-Sheet 1 FIGURE I GAS- PHASE COCURRENT ALKYLATION LIQUID RECYCLE I77 (ISOBUTANE) I742 HBUTANE REACTOR COMPRESSOR ISOBUTANE I04 26,700 cu. F1. 4 BICONDENSER BUTANE-BUTYLENE 429 I Am 624-3 DIB TOWER H so MAKguP 96 G5 G5 I ALKYLATE 446.5 ,96.8 SPENT VH2 S04 ALL FLOWRATES EQUIVALENT LIQUID BBL/HR.

Dec. 18, 1973 J. W. MILLER GAS-FOG ALKYLATION WITH STRONG SULFURIC ACID AND PHOMOTER Filed May 5, 1972 4 Sheets-Sheet 2 FIGURE 2 PRIOR ART ALKYLATION LIQUID RECYCLE (ISOBUTANE) 3722 .5

REACTOR ISOBUTANE I697 |O,40O u 11 BUTANE-BUTYLENE 435. 50 PSIG H 80 MAKEUP 96 50 F ALL FLOWRATES EQUIVALENT LIQUID BBL/ HR.

COMPRESSOR 4 a CONDENSER 2664.5

96.8 SPENT H2804 Dec. 18, 1973 J. W. MILLER GAS-FOG ALKYLATION WITH STRONG SULFURIC ACID AND PROMOTER Filed May 5, 1972 FIGURE 5 BUTENE ISOBUTANE 4 Sheets-Sheet :5

ALKYLATE ACID Dec. 18, 1973 J. w. MILLER 3,780,130

GAS-FOG ALKYLATION WITH STRONG SULFURIC ACID AND PROMOTER Filed May 1972 4 Sheets-Sheet 4 FIGURE 3 UNREACTED GASES DISCHARGE RING\ 4 1 ms INLET- (ISOBUTANE BUTIYLENE CONCENTRATED H2304 4- IO 7 KV,DC

ACID ALKYLATE FIGURE 4 4- I0 KV,DC GASES 4\ I I I EXCITER RING l I COLLECTOR RING l UNREACTED GAS TO RECYCLE ACID,ALKYLATE SEPARATOR United States Patent O 3,780,130 GAS-FOG ALKYLATION WITH STRONG SULFURIC ACID AND PROMOTER Jaydee W. Miller, Wallingford, Pa., assignor to Sun Oil Company of Pennsylvania, Philadelphia, Pa. Continuation-impart of application Ser. No. 150,607, June 7, 1971, now Patent No. 3,717,686, dated Feb. 20, 1973. This application May 5, 1972, Ser. No. 250,718

Int. Cl. C07c 3/54 U.S. Cl. 260683.63 11 Claims ABSTRACT OF THE DISCLOSURE A process for alkylation of gaseous C -C monoolefin with gaseous C -C branched parafiin comprises contacting the mixed gases at alkylation conditions with a fog or mist of strong sulfuric acid and a promotor. The promoter may be red oil or spent acid from a conventional sulfuric acid alkylation or from a previous run of the present process. Preferably, the catalyst and hydrocarbon reactants are maintained in a concurrent flow. For C or C acyclic monoolefin and C or C isoparaffin, the preferred alkylation conditions include a temperature in the range of about 3080 F. and a pressure about atmospheric (e.g., 5-25 p.s.i.a., typically 14-20 p.s.i.a.). The feed mole ratio, paraffin to olefin, can be in the range of 1:1 to 60:1, typically 2:1 to 30:1. Liquid paraflin (e.g., isobutane) can be injected into the reactor in order to control the reaction temperature. Preferably, the liquid acid droplets have a mean diameter in the range of 5-50 microns, typically -25 microns. An advantage of the present process is a substantial savings in distillation costs required to separate isobutane from the product.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my application Ser. No. 150,607, filed June 7, 1971, which issued as U.S. Pat. 3,717,686 on Feb. 20, 1973 and is related to later-filed application Ser. No. 354,559, filed Apr. 26, 1973, which claims certain apparatus which can be useful in practice of the present process.

BACKGROUND OF THE INVENTION Paraffin-olefin alkylation, on a commercial scale, is done with reactants in the liquid phase. Reactants are usually iso-butane and butylene (usually a B-B stream, e.g., containing about 35 volume percent butenes, the remainder mainly isobutane). The catalyst is liquid sulfuric acid or liquid hydrogen fluoride. The process is well known and has been successfully operating since the 1940s. In contrast, no successful commercial process has involved a fog phase acid catalyst, despite teachings of a gas phase alkylation using a hydrogen fluoride/ fog catalyst.

The prior art (e.g. U.S. 2,378,439 to C. H. Schlesman, issued June 19, 1945 and U.S. 2,437,544 to M. M. Marisic, issued Mar. 9, 1948) has taught the alkylation of paraflins with olefins by contacting them with a fine spray or a fog of liquid phase hydrogen fluoride. Such art does not teach the alkylation of paraffins with olefins using a fog of concentrated sulfuric acid at about atmospheric pressure. However, "U.S. 2,378,439 suggests using a hot ICC sulfuric acid spray to polymerize isobutylene but does not teach that a sulfuric acid fog can catalyze paraffin-olefin alkylation. Nor does the prior art appreciate the importance of concurrent flow of the catalyst fog and the hydrocarbon reactants (for example, U.S. 2,437,544 utilizes a countercurrent flow). Nor does the prior art appreciate the importance of dispersing such a liquid acid catalyst into droplets having a mean diameter in the range of 5- 50 microns (preferably using electrostatic means of dispersing the liquid acid). Regarding the prior art, it should be noted that hydrogen fluoride is a stronger acid than sulfuric acid (e.g., U.S. 2,437,544 suggests use of a combination of HF and H 50 but not H alone, presumably due to the stronger acidity of HF) and is far more volatile, having a much lower boiling point and higher vapor pressure than sulfuric acid. These characteristics have apparently lead the art away from equating HF and H 80, in gas-fog phase alkylation.

SUMMARY OF THE INVENTION A process for alkylation of gaseous C -C monoolefin with gaseous C -C branched parafiin comprises contacting the mixed gases at alkylation conditions with a fog or mist of strong mineral acid, preferably strong (e.g., sulfuric acid. Preferably, the catalyst and hydro carbon reactants are maintained in a cocurrent flow. For C or C acyclic monoolefin and C and C isoparaffin, the preferred alkylation conditions include a temperature in the range of about 3080 F. and a pressure about atmospheric (e.g., 5-25 p.s.i.a., typically 14-20 p.s.i.a.). The feed mole ratio, paraflin to olefin, can be in the range of 1:1 to 60:1, typically 2:1 to 30:1 Preferably, the liquid acid droplets have a mean diameter in the range of 550 microns, typically 10-25 microns. For example, isobutane can be premixed with butylenes at the desired mole ratio and the gaseous mixture reacted in the presence of a fog of sulfuric acid droplets of about 10 microns in diameter at atmospheric pressure and 50 F. The product contains about 30-40% isobutane and the remainder is alkylate; Whereas, the product from conventional liquid phase sulfuric acid alkylation contains 8085% isobutane.

Alkylate and isobutane are separated by distillation, the isobutane being recycled to the reactor. This distillation step is a major process cost in both the present process and in conventional alkylation. Since less (30-40% vs. 80-85%) isobutane must be removed in the present process, a substantial heat saving is realized in distillation costs.

The reacting gases, e.g., isobutane and butylene, can be pre-mixed and then reacted with a fog of sulfuric acid droplets. The droplets can be generated by electrostatic methods, for example, they can be generated by the means of producing a charged aerosol taught in the US. patents to A. M. Marks, U.S. 2,638,555, issued May 12, 1953 and U.S. 3,297,887, issued-Jan. 10, 1967 or of A. M. Marks and E. Barreto, U.S. 3,191,077, issued June 22, 1965. The aerosol or fog need not necessarily be charged; therefore, for the present process an alternating current can be used instead of the direct current in these devices of these patents, thus, generating an uncharged aerosol. The charged aerosol is preferred; however, because the droplets can be directed to a discharge device (having an opposite charge to that of the droplets, thus, facilitating separation of the catalyst from the reaction mixture).

One of the advantages of this gas-fog process is that the liquid product (e.g., alkylate-isobutane mixture) can contain only about 30-40% (by volume) isobutane (e.g., the equilibrium solubility mixture at 50 F. and 1 atm. pressure). The mixture in a conventional alkylation plant leaving the reactor is about 80-85% isobutane in alkylate due to the necessary higher pressure.

In the present process, the dilution effect of the isobutane is greater than would be anticipated. In a typical commercial H 80 alkylation plant, the minimum pressure in the reactor is about 25 p.s.i.a. and in the frontend of the system 40 p.s.i.a. is typical. In either process, feed isobutane in excess of that which can be dissolved in the product alkylate can be removed from the reactor, as a gas, and, if desired, recycled to the reactor. However, in the present process, excess gaseous isobutane can fill the reactor volume and act as a diluent; thus, permitting a lower paraffin/olefin ratio in the feed to the reactor and improving product quality.

In conventional alkylation a large excess of isobutane is required in the reaction mixture to produce high octanenumber product in satisfactory yield. This required excess of isobutane is obtained by:

(1) Operating at high (50 p.s.i.g.) pressure to keep most of the reactor contents in the liquid phase.

(2) Recycling from 5-10 volumes of isobutane per volume olefin feed, and

(3) Various internal crossand counter-flow process arrangements.

The net result is that the reaction mixture typically contains 80-85 vol. percent isobutane which must be separated from the product alkylate by distillation, a major process cost.

In the present process, a large excess of isobutane also is required. However, in the present process, this excess is in the gas phase. Since the product leaves the reactor as a saturated liquid, it contains only the amount of,isobutane which is in vapor-liquid equilibrium at reaction temperature and (low) pressure (15-40 p.s.i.), i.e., about 30-40 vol. percent. Instead of utilizing a large recycle stream of isobutane, this process provides excess residence time in the reactor, above that required for complete reaction. This excess residence time translates to a reactor volume sufficient to contain the large excess of isobutane needed for dilution.

In this process, as in conventional alkylation, isobutane is separated from the reaction product by distillation. Since less isobutane must be distilled, substantial heat havings are realized at this step.

The cost savings in steam (e.g., about /bbl. of alkylat'e) on a 10,000 b./d. alkylate plant are estimated as being at least $300,000/year.

Another feature of one embodiment of the present invention is the injection of liquid paraffin, preferably C -C (e.g., n-butane, n-pentane and isobutane) into the reaction zone to control the temperature (e.g., remove the heat of reaction by vaporization of some or all of the liquid paraffin).

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings,

FIG. 1 is a schematic representation of an embodiment of the process of the present invention, involving cocurrent contact of a gaseous mixture of isobutane and a socalled B-B feed comprising butane and butylenes. The numbers are related to the illustrative examples and indicate the flow rates of the catalyst, feed materials, product, etc., each in the equivalent of liquid barrels per hour.

FIG. 2 is a schematic illustration of a typical prior art liquid phase commercial sulfuric acid alkylation process capable of producing the same output of alkylate as the process embodiment of the present invention illustrated in FIG. 1. As is discussed, supra, in the illustrative examples (see material and heat balances, Tables IV and V) these drawings aid in comparing the advantages of the present process with that of the prior art.

FIGS. 3 and 4 are schematic illustrations of two types of reactor systems including electrostatic fog-producing means, which can be used in the process of the present invention (as, for example, in the process illustrated in FIG. 1).

FIG. 5 is a schematic illustration of apparatus referred to in the illustrative examples.

FURTHER DESCRIPTION OF THE INVENTION I have discovered that an electrostatic fog-producing device can provide nearly perfect mixing between the fog of acid catalyst and a hydrocarbonaceous gas phase feed flowing cocurrently, thus, greatly improving the speed of the reaction and decreasing the necessary reactor volume needed to produce a given output of alkylate. The fog can be produced by passing a liquid through a hollow needle that is charged with about 2,000 to 8,000 volts D.C. The liquid on leaving the needle is dispersed into very small droplets. The size of the droplets depends on the voltage, but sizes of the order of 10 microns can be obtained (the limit of particle visibility in a strong light). Alkylation of monoolefin with isoparafiin is a mass transfer limiting reaction. The alkylation reaction is thought to occur at the acid hydrocarbon interface, and to be rate controlled by hydrocarbon difiusion to the interface or into the acid. The electrostatic fogger is a useful means of conducting such an alkylation. That is, the rate of alkylation of butylenes with isobuane is believed to be limited by a process of mass transfer for hydrocarbon reactants across the hydrocarbon-acid interface into the acid phase. The electrostatic fogger produces very small particles of acid with very large specific surface area. The large specific surface area facilitates the mass transfer process which limits the reaction rate, therefore, the electrostatic fogger is a particularly useful means of conducting such an alkylation.

A gas-fog phase alkylation reactor, including an electrostatic fogging means can be used to produce gasoline boiling range alkylate from isobutane-isobutylene gas mixtures and sulfuric acid dispersed as a fine mist or fog. The acid is dispersed into a fog with a direct current high voltage charge. Acid fog can be continuously produced and the reactant gases flowed cocurrently with the fog. Mixture ratios of isobutane to isobutylene can be varied, for example, from 2:1 to 30:1. The temperature of reaction can typically be from 30 F. to F. The pressure is preferably atmospheric, although higher or lower pres sures can be used.

Alkylate quality (e.g., maximum percent C -C and minimum percent (3 can be comparable to conventionally produced alkylate using the same reactant gases. Preferred reaction conditions for producing alkylate of a similar type (but typically superior in octane rating) to commercial alkylate (as illustrated by Example I and II herein) comprise an isobutane/olefin ratio of about 1020:1; temperature of about 30-35 F. and pressure of about 1 atmosphere. If isobutylene were the olefin in a conventional sulfuric acid alkylation process, the produce alkylate would contain about 35% C alkylate produced by the present process from isobutylene can contain about 30% 0 It is generally believed by those skilled in the alkylation art that an isobutylene feed provides the most severe test of an alkylation process. If a process produces high quality alkylate on this feed, as my process does, it will perform even better on other olefin feeds.

It is well known that isobutylene is the poorest of the 3 C olefins as an alkylation feed. This is because re-. ported alkylate quality (maximum percent C -C and minimum percent C is lowest. Therefore, isobutylene is not used alone as a commercial alkylation plant feed. However, the art does give results of commercial operation on isobutylene feed, and when these results are compared with my results using the present process in illustrative Examples I and 'II, it is seen that the product of the present process is superior in quality. Illustrative Example III is a process design based on Examples I and II, and shows the source of the cost saving when using the present process.

Cost savings on the de-isobutanizer distillation column can be realized because of gas phase operation. The calculated savings are about per barrel of alkylate. These savings are realized in decreased steam requirements on the DIB (i.e., de-isobutanizer) tower. That is, Example III shows that the heat saving in the distillation step amounts to about 142 lb. steam/bbl. alkylate. This saving is offset slightly, yielding a net cost saving (at 80 M# steam) of 10 (bbl. alkylate) or $300,000/yr. for a plant of 10,000 b./d. capacity. This savings of about 10 per barrel is a significant decrease and indicates that the economics of the present process are at least as attractive as those of the more modern hydrofluoric acid plants. Another advantage is that the present process can utilize a less expensive (although somewhat larger in volume) reactor vessel than is required in conventional liquid phase reaction. That is, since the present process can be run at atmospheric pressure, expensive pressure reactors and associated equipment are not required. Furthermore, the conventional alkylation requires expensive homogenization mixers to insure good liquid-liquid contacting. The present process can be run using a potentially less expensive mixing system (e.g., the electrostatic for generator) ILLUSTRATIVE EXAMPLES Example I A reactor system similar to that of FIG. 5 was set up, including an electrostatic fog generator. The reactor system comprised means (1, 2, 2a, 3) for feeding liquid acid to the electrostatic fog generation means (7, 8, 9, 9a, 10, 11, 12, 13), means (20, 21, 22, 23, 24, 25, 26, 27, 28, 29) for mixing and feeding olefin and paraifin to the reactor means (4, 5, 6) and means (14, 15, 16, 17, 18, 19) for venting unreacted gases and for collecting the alkylate product and the spent acid.

The means illustrated in FIG. 5 can be the following:

1-Stopcock and drain 2Sulfuric acid reservoir 3a-Transfer line 3-Connector 4--Hydrocarbon feed port 5Inlet acid tube and needle 6Reaction vessel 7High voltage electrical lead 8-I-Iigh voltage source 9, 9a, 10, 12, 13Electrical ground connections 11-Collector ring 14, 15Stopcocks and transfer lines (product) 16-Acid collection line 18-Acid collection reservoir 17-Alkylate collection line 19-Alkylate collection reservoir 27, 24, 23, 20Hydrocarbon gas feed line 21'Hydrocarbon gas mixing vessel 22-Mixer motor 25-Reactant butylene reservoir 28Reactant isobutane reservoir 26, 29-Stopcock and drain.

All parts were of Teflon and the walls of glass. The exciter ring 11 and discharge ring 13 of the fog generator were of 316 stainless steel. The inlet acid tube and needle 5 were of 316 stainless. The effective reactor volume (i.e., free space) was 100 cc. The acid reservoir 2 was a 500 cc. stainless Hoke bomb. All external tubing was stainless.

Sulfuric acid was reagent grade (98% min.); isobutylene was CP grade from Matheson Chemical Company.

Isobutane was a technical grade Sun Oil Company refinery product (about pure).

This reactor did not include means for cooling the reacting volume. The purpose of this reactor and the testing done therewith was to establish that the present process was operable. This testing was not intended as a means of process optimization (as was done to some degree in later work reported herein).

During operation of the reactor, liquid hydrocarbon product was qualitatively analyzed using a vapor phase chromatograph (VPC). The column had a simple boiling point separation packing. The product VPC scan could be compared with a scan of commercial alkylate from a BB stream and, thus, indicate whether product was similar. When product from the reactor was similar to the plant alkylate, a comprehensive analysis was made of the compounds in a sample of the product.

Before any reactant gases were admitted, the system was thoroughly purged with nitrogen. After about 30 minutes of purging with nitrogen, the acid flow was started at the desired rate. Isobutane was introduced and the power supply was turned on and set at the desired level (about 4,0006,000 volts) and below the level Where arcing would occur. The system was allowed to operate for a few minutes to come to steady state operation. The atomization was observed to insure that the acid was atomized correctly. When correct atomization was achieved, the acid drops were so fine that they were invisible. When correct atomization was reached, the isobutane rate was readjusted and set at the desired level, then the isobutylene was turned on at the desired level. In the gas liquid separator at the bottom of the reactor, unreacted gases were vented off and the liquid product was collected at the bottom.

During the runs, the acid layer was periodically drawn off through a stop cock at the bottom. When necessary, the organic layer could also be drawn off. A run usually lasted about 10-20 minutes. On approaching the end of the run period, the stop cock would be left open for a while to drain out all material. The organic material was immediately sampled assayed on the VPC.

If the scan looked promising, the sample was retained for comprehensive analysis. If poor, the sample was discarded, in general, product volumes were of the order of .2 cc.

After closing the sample stop cock, voltage, reactant gases and acid were turned oif. About 30 minutes would elapse between tests to allow the reactor to drain all liquids. In some runs, the acid would coat the glass walls of the reactor. When this occurred, the reactor was disassembled and cleaned in order that acid coating the walls would not alter the reaction conditions and, thus, not provide a reaction representative of gas-fog phase conditions. During the draining periods, nitrogen was used to purge the system. Then the run procedure was repeated with a new set of reaction conditions.

A total of 35 scouting runs was made. These runs were designed to prove operability of the process and to indicate operating conditions for production of high quality alkylate. A high quality alkylate was defined as a material that had a VPC scan similar to a scan of the commercial alkylate. By this procedure, it was found that the mixture ratio of alkane to olefin was the main variable in determining the quality of the alkylate. This ratio for good results was in the range of 8:1 to 30:1 and for best results was about 10-2'0 moles parafiin (isobutane) to 1 mole olefin (isobutylene). Since the other C, monoolefins are known to be less likely to polymerize than isobutane, with most catalysts, it is very likely that lower ratios (e.g., 3 l-8 1) will produce useful alkylate with a B-B stream.

Other variables that affected quality, but to a much lesser degree, were acid rate, and temperature of incoming gases. In general, acid rates of .03-.3 cc./min. were used and quality was somewhat constant for these values. At the higher acid rates (0.3 cc./min.), the walls of the reactor would become coated with acid and most of the reaction would occur on the walls and quality would go down. When incoming gases were cooled to 32 R, an increase in quality was observed. This demonstrated the importance of cooling.

Voltage on the needle (the acid entrance) had no effect on quality except at higher voltages (4,000-5,000-) where arcing could occur and temporarily change the atomization. Current was usually about -70 mircoamps.

Table HI provides a comparison of the composition, by gas chromatography, of'alkyiate produced in this scouting reactor with an alkylate produced commercially with iso-butylene feed. The fog phase alkylate is an average of three products from three separate runs. The published value has all the C and C fractions removed. The fog phase samples were prepared by allowing the product alkylate to come to room temperature equilibrium, there- TABLE I.SUMMARY OF RUNS IN EXAMPLE 1 Total Inlet gas gas Run flow temp. Acid flow Moles Percent Product VPC compared with F. (cc/min.) lIC4= 0 standard 60 04 9/1 Very poor product quality. 60 04 12/1 Product formed on wall, poor qulaity. 60 .04 20/1 No product formed. 60 04 3/1 Quglitg poor, but yield of liquid 1g 60 .04 8/1 80 Quality poor. 60 .04 20/1 80 Do. 60 04 /1 80 Do. 40 04 /1 70 Quality improved. 40 04 20/1 70 Do. 40 05 /1 67 Do. 06 20/1 87 Quality poor. 40 04 5/1 87 Do. 40 04 10/1 56. 5 Quality improved.

NorE.Voltage 4,0006,000 volts.

Typical examples of both successful and unsuccessful runs are given in Table I. These runs establish feasibility of the process in at least this range of conditions:

iC /C 8:1 to 30:1 mol ratio. Acid rate 0.03-0.3 cc./min. Voltage 4,0006,000 c. at 1070 microamps.

Although some unsuccessful runs also occurred in this range of conditions, feasibility was established and a more refined study conducted as described in Example II.

Example II A larger reactor was constructed, similar to that of Example I, except that the reactor had another tube inside the acid tube to permit controlled addition of liquid isobutane. As the butane vaporized, it extracted the heat of reaction, thus, controlling the reaction temperature. In this reactor, the temperature of reaction zone could be controlled with liquid isobutane. Using this cooled reactor, a series of 15 tests was run. Some of the tests were aborted because of shorting from the needle to ground, but the product from the remaining tests was similar to product from commercial prior art sulfuric acid, liquid phase, alkylation using the same feedstocks. Table II summarizes the tests from this reactor.

TABLE III Fog phase alkylate Commer- A B cial 1 Total 98. 5 100. 0 100. 2

Percent olefin 1. 5 2. 7 TMP/DMH 2 5. 93 5. 93 5.

l L. F. Albright, Chemical Engineering, 10/10/66, pp. 2 Ratio trimethyl pentanes/dimethyl hexanes.

TABLE IL-SUMMABY OF RUNS IN EXAMPLE 2 [Liquid isobutane injection for cooling] Gas equi- Total flow valent of Total gaseous mix injected moles Acid flow Percent (cc/min.) liquid i0; iC /iO (cc/min.) 09+ Product quality 1 100 2, 000 20/1 25 Very poor quality.

Electrical shorting occurring.

1 200 1, 600 8/1 25 85+ Poor quality. 2, 200 2, 000 20/1 10 28. 1 Excellent quality. 2,200 2, 000 20/1 10 40.4 Good quality. 3, 400 800 20/1 28 63 Do. 3, 400 800 20/1 50 62 Do. 3, 400 800 20/1 28 Poor quality.

3, 160 400 17/1 30 56 Good quality. 3, 000 800 18/1 30 58. 4 Do.

1, 700 400 20/1 25 71. 3 Poor quality.

1, 700 400 20/1 075 38. 7 Good quality.

1, 600 1, 500 30/1 19 18. 3 Excellent quality. 2, 700 1, 500 20/1 20 21. 6 D0. 3, 000 1, 500 8/1 15 28 Do.

2, 700 1, 500 20/1 50 76. 9 Poor quality.

1 isobutylene.

9 Example III In the accompanying drawings, FIG. 1 is a flow sheet of the embodiment of the present process and FIG. 2 illustrates, for comparison, conventional liquid phase H 80 alkylation. In both figures streams are numbered for comparison. The identification numbers also are found in the column headings of Table -IV which shows a material balance of each such process. Table V shows a heat balance around the DIB tower in each such process and shows the decreased heat load which is obtained with the process of the present invention. These calculations show that the gas-fog phase alkylation of the present invention can save about per barrel of product due to decreased steam consumption to the DIB tower.

An important point to note in Table 4 is the realtive TABLE IV Cit In a 10,000 b./d. plant operating 3-00 days/year, this saving amounts to $300,000 B/yr.

A minor amount of red oil or spent acid (from conventional sulfuric acid alkylation or from a previous run of the present process) can be added to the H SO catalyst to aid in starting" the alkylation process (e.g., 10 parts used acid added to 300 parts (by volume) of fresh acid).

Gas phase sulfuric acid alkylation process-material balance Stream-All flowrates in bbl./hr.

1 2 3 4(0) 5(A) 6(D) 6 7 8(E) 11(B) 12(B) Eflilu- Acid B-B Iso- Liquid Reactor ents DIB Isobutane 7 V feed butane recycle vapor liquid feed recycle n-Butane Alkylate Makeup Spent Component:

Total B/H. 429 109. 4 1, 742 1, 565 625. 1 624. 3 177 30. 8 416. 5

B/SD r Y 10, 000 Lb./hr 87, 865 20, 650 34, 909 6, 292 101, 898 225(F) Conventional sulfuric acid alkylation, design basis-Material balance Component:

0 and Ltr. 6. 5 11. 7 404 301 103 103 1 18. 2 l-C 142 114 2, 798 1, 094 1, 076. 7 1, 704 2. 7 1-C 223 n-C 60 43. 5 515 165 452. 4 350 85 11-0 4 5 4. 5 4 25. 0 0.5 1. 3 n-OL 15. 7 n-C 16. 7 n-C 1 306. 9 0. 7 n-CH- 38. 1 Acid 96.

Total B/H 435. 5 169. 7 3, 722. 5 1, 565 2, 664. 5 2, 157. 5 107. 9 416. 5 96 96. 0

B/ 10, 000 Lb-Ihl 427, 570 21, 265 101, 730

1 Sum of butane plus propane purges.

(A)=Excluding acid; (B)=Net quantities only; (C)=In equilibrium with stream 5; (D)=Saturated liquid, 1 atm., 50 F.; (E) =Typica1 alkylation plant product; (F) =Assume 226#/hr. loss as acid sludge.

Table V is a heat balance about the DIB tower for the 5 processes of FIGS. 1, 2. This table shows a saving of in a plant of 10,000 b./d. alkylate capacity. The 59.4 MM B.t.u./hr. equals about 59.4 M#/hr. of steam (at 1,000 B.t.u./lb.), or

lb. steam bbl. alkylate 416.5 b./hr.

practical (e.g., fog-phase).

,TABLE V Heat balance-DIE tower Conventional design Fog phase design Heat duty Heat duty, M Temp. M M Temp. MM Outputs or heat use 1b./l1r. range, F. b.t.u./hr. 1b./hr. range, F. b.t.u./hr.

Sensible heat (product-feed T):

Alkylam 101. 7 50-180 6. 6 101. 9 50-180 6. 6 Butane l8. 50-100 0. 52 6. 3 50-100 0. 18 Isob 427. 5 50-65 3. 65 34. 9 50-65 0. 3

Total 547. 7 (10. 77) 143. 1 (7. 08)

Latent heat (condenser duties):

nfmm 18. 5 3. 1 6. 3 1. 05 Isobnfane 427. 5 58. 5 34. 9 4. 77

Total. (61. 6) (5. 83)

Grand to 72. 37 12. 91

NOTES:

Steam comes in at 400 p.s.i.g. and drives compressors and leaves at 40 p.s.i.g. h (400 p.s.i.g. sat.) "1204. 5 h (40 p.s.l.g. sat.) 1169. 7

Ah 34. 8 b.t.u./ x 55.5 M /hr. =1.93 MM B.t.u./hr.=758 HP.; 566 kw.

The invention claimed is:

1. Process for alkylation of gaseous C -C acyclic monoolefin with gaseous C C branched parafiin, said process comprising contacting, in a reactor vessel, said monoolefin and said paraflin in the presence of a fog consisting essentially of strong sulfuric acid and a promoter under alkylation conditions, said promoter being selected from the group consisting of red oil and spent sulfuric alkylation acid.

2. Process of claim 1 wherein said sulfuric acid, paraflin and monoolefin are maintained in cocurrent flow until the alkylation reaction is completed.

3. Process of claim 1 wherein said alkylation conditions include a temperature in the range of 80 F.,

a pressure in the range of 5-25 p.s.i.a., and a feed molar ratio of paraffin to olefin in the range of 2:1 to 30: 1.

4. Process according to claim 1 wherein said forg consists essentially of sulfuric acid droplets having a mean diameter in the range of 5-50 microns.

5. Process according to claim 3 wherein said monoolefin consists essentially of C or C monoolefin, or a mixture thereof, and said parafiin consists essentially of C 7. Process according to claim 3 wherein said pressure is in the range of 14-20 p.s.i.a.

8. Process according to claim 1 wherein a parafiin hydrocarbon in liquid phase is injected into said reactor vessel to control the temperature of the reaction. 7

9. Process according to claim 1 wherein said paraffin consists of isobutane.

10. Process according to claim 1 wherein said fog is generated by electrostatic means.

11. Process according to claim 1 wherein said fog consists of a charged aerosol and wherein said reactor contains collector means including means for discharging the charge after alkylation has occurred.

References Cited UNITED STATES PATENTS 2,437,544 3/1948 Marisic 260683.63 3,053,917 9/1962 Bergougnou 260-68359 3,082,274 3/1963 Mayer 260-68359 3,234,301 2/1966 Goldsby 260-683.62 3,717,686 2/1973 Miller 260683.59

DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant Examiner 

